The spring plant sale at the UCR Botanic Gardens will celebrate its 40th anniversary Saturday and Sunday.

Nearly 10,000 plants, including many rare and unusual varieties and old favorites, will be on sale from 11 a.m. to 4 p.m. Saturday and 9 a.m. to 3 p.m. Sunday. There is no charge to attend the sale but it costs $2 to park on campus.

The plant selection includes colorful, heat-loving trees and shrubs, flowering perennials, miniature roses, rare cacti and other succulents, patio and houseplants and wildflower seeds. In addition, a selection of showy, water-efficient, heat-loving and California native plants selected for spring planting will be available.

Most of the plants for sale will have a detailed information sign and color photo to help make selections. A detailed plant list is available at http://gardens.ucr.edu/.

Volunteers with the UC Cooperative Extension Riverside County Master Gardener Program will sell more than 100 varieties of heirloom tomatoes, herbs, vegetables and beneficial flowers.

There will also be a series of free classes during the plant sale. Following is the class schedule.

11:30 a.m. Saturday, Design a Water-Wise Garden with Color Year-Round, presented by Nan Simonsen, a master gardener who owns Nanscapes, a garden design business in Riverside.

2 p.m. Saturday, Edible Landscaping – Eat Your Yard, presented by Christine Markel Lampe, a master gardener with a home garden that is beautiful and edible.

10 a.m., noon and 2 p.m. Sunday, Tomatoes, a children’s class.

11 a.m. Sunday, Creating a Fairy Garden, presented by Dona Jenkins, a master gardener and the owner of GardenMoonlight, which is dedicated to creating magical and whimsical gardens.

1 p.m. Sunday, Planting a Summer Vegetable Garden, presented by Lucy Heyming, a master gardener who is the host of “Gardening with Lucy” on the city of Riverside cable channel.

The botanic gardens cover more than 40 acres and feature nearly 3,500 plant species from around the world. The gardens have many scenic trails, including gentle pathways graded for wheelchair access. A wide array of blooming plants can be seen the year around.